The present invention relates to a side airbag apparatus that inflates and deploys an airbag in a space between a side door and an occupant seated in a vehicle seat when an impact is applied from a side of the vehicle due to a side collision, thereby reducing the impact using the airbag to protect at least a shoulder of the occupant.
A side airbag apparatus is effective as means for protecting an occupant seated in a vehicle seat when an impact is applied to the vehicle from a side due to a side collision. Such a side apparatus includes an inflator that discharges inflation gas in response to an impact to inflate and deploy an airbag in a narrow space between an occupant and a side door. One type of such airbag apparatuses includes an airbag with a shoulder protecting portion, which is inflated and deployed beside at least a shoulder of an occupant (for example, refer to Japanese Laid-Open Patent Publication No. 2003-261000).
The airbag of the side airbag apparatus disclosed in the above publication is formed by joining a fabric sheet on a vehicle inner side and a fabric sheet on a vehicle outer side at peripheries. Each fabric sheet has such a size that it can be inflated and deployed beside a region ranging from the shoulder to the lumbar region of an occupant. The fabric portions are joined to each other at a center portion in the vertical direction by a lateral U-shaped inner joint portion. The inner joint portion divides the airbag into a thorax protecting portion, a shoulder protecting portion, and a lumbar region protecting portion. The thorax protecting portion is surrounded by the inner joint portion and is inflated and deployed beside the thorax of the occupant. The shoulder protecting portion is located above the inner joint portion and is inflated and deployed beside the shoulder of the occupant. The lumbar region protecting portion is located below the inner joint portion and is inflated and deployed beside the lumbar region of the occupant. In the apparatus of the above described publication, the inner joint portion is referred to as a seam, the thorax protecting portion is referred to as an intermediate chamber, the shoulder protecting portion is referred to as an upper chamber, and the lumbar region protecting portion is referred to as a lower chamber.
The above described airbag is inflated and deployed such that the upper end of the inner joint portion, that is, the boundary between the shoulder protecting portion and the thorax protecting portion, is located beside and in the vicinity of the top of the door trim of the side door.
When the side door bulges into the passenger compartment due to a side collision, the airbag is pushed in the same direction. At this time, the shoulder protecting portion of the airbag is prevented from moving inward in the passenger compartment by the shoulder of the occupant. Therefore, the shoulder protecting portion falls toward the outside of the vehicle while pivoting on the boundary between the shoulder protecting portion and the thorax protecting portion (the upper end of the inner joint portion). The fallen shoulder protecting portion contacts the top of the door trim and moves toward the vehicle outside while contacting the top. That is, the shoulder protecting portion slides along the door trim. The shoulder protecting portion thus can hardly exercise the function for protecting the shoulder of the occupant from a side collision in a satisfactory manner.